If you are a Premium member and the credit card used for your membership subscription has been replaced or changed, you need to update your payment information before the next membership renewal.
Depending on the payment method, there are several ways to update credit card info.
Subscriptions Purchased on iOS App Store
All App Store payments, including credit card information, are handled by Apple. Please see Change, add, or remove Apple ID payment methods Apple's support article.
Subscriptions Purchased on Google Play
Similar to the App Store, all Google Play payments including credit card information are handled by Google. Please see Change, add, or delete credit/debit card Google's support article.
Subscription Purchased on MyNetDiary.com
We use Paddle\PayPal as the credit card processor and do not store any credit card numbers, so there is no risk of unauthorized access to credit card information when you use the app.
If you have a PayPal account, you can go to PayPal.com, sign in to your PayPal account, and update your payment methods.
If you don't have a PayPal account, please wait until your current subscription expires and you move to the free tier. After that, you can re-subscribe using your new credit card information or use your PayPal account.